Land-based vehicles may often travel through water. Some vehicles, such as off-road vehicles, may be designed to travel through a specified depth of water, referred to as a maximum wading depth, and in preparation may comprise suitably sealed closures to prevent water damage to vehicle compartments and vehicle electronics. Encountering a level of water beyond the maximum wading depth may pose a risk of engine damage. In situations of a vehicle wading, a driver of the vehicle may typically be uninformed of the precise depth of water which the vehicle is about to enter or is already traveling in.
As such, various attempts have been made to determine wading depth for vehicles. One example approach shown by Clarke et al. in U.S. 2015/0046032 A1 discloses a vehicle system that determines a possibility of the vehicle entering into a wading situation. By employing remote ranging sensors to detect the presence and the depth of water in which the vehicle is traveling, the system may take precautionary measures so as to prepare the vehicle for possible wading. Therein, vehicle operations may be adjusted to activate an internal combustion engine from an electric only driving mode, suspend a stop-start fuel saving mode, and/or actuate a ride-height adjustment.
However, the inventors herein have recognized potential issues with such systems. As one example, off road vehicles designed to travel through a finite wading depth may encounter higher than maximum wading depth levels of water, such as when driving through a flooded area or during flash floods, or when backing up into a body of water such as during a boat launch procedure. Further, even if precautionary measures such as those stated above were adopted, water may enter into the evaporative emission control system in vehicles driven through high water. For example, water may enter the fuel system and eventually the engine via a vent port during a purge operation. During purging mode of a vehicle, a fuel vapor canister packed with adsorbent may allow the adsorbed vapors to be purged by fresh air, taken in via the canister vent port and a vent line inlet into the canister from where a fuel-air mixture may be purged into the engine intake manifold for use as fuel. In the event of entry of water into the evaporative emission control system, if water were permitted to make contact with the adsorbent material, the adsorbent would no longer function to adsorb fuel vapors. Additionally, water may be sucked via a canister purge valve into the combustion cylinders due to the vacuum existent in the intake manifold causing a hydrolock situation.
In one example, the issues described above may be addressed by a method for a vehicle comprising adjusting a valve in a fuel system of a vehicle responsive to a level of water through which the vehicle is passing. The valve in the fuel system being adjusted may be a canister purge valve or a canister vent valve. In this way, the method may shut off fuel vapor purging when a vehicle is traveling in high water to prevent the sucking of water into the fuel vapor canister and into the engine intake manifold, thereby preventing degradation to the fuel vapor canister and preventing engine hydrolock.
As one example, a proximity sensor may be employed to detect a depth of water during forward driving. The proximity sensor may be used for estimating a distance to objects when the vehicle is in reverse gear and the sensor is horizontally-facing, such as a backup sensor. The sensor may be repurposed and adjusted to a vertically-facing position to detect a distance to a nearest surface during forward drive of the vehicle. In the event of the vehicle traveling through high water, the proximity sensor may estimate a distance to water and calculate a water level (e.g. depth/height of water above ground) through which the vehicle is traveling. The water level, if determined to be above a first threshold, may be high enough such that water may be introduced into the evaporative emission control system and therefore as a precaution, purge operations may be disabled by closing of a canister purge valve (CPV) and/or the canister vent valve (CVV). Further, a determination of water level above a second threshold may indicate the water level is high enough to be introduced into the engine air intake. Therefore, as a precautionary measure the engine may be strategically shut-off to prevent hydrolock.
Thus, by suspending purge operation when a vehicle is in water exceeding the first water level threshold, and by further shutting off the engine when the water level exceeds a second threshold, the risk of water inhalation into the evaporative emission control system and the engine air intake may be mitigated. Additionally, using the proximity sensor as a backup sensor during reverse drive and by repurposing the existent proximity sensor to face vertically during forward drive to detect distance to a nearest ground surface in real time eliminates the need for additional sensors and/or equipment. The proximity sensor when vertically-facing may provide a reliable estimation of proximity to the nearest surface (e.g. distance from the sensor to water for a vehicle driving in water), responsive to which fuel vapor purging may be disabled. In this way, the vehicle components, specifically the evaporative emission control system and the engine air intake system, may be prepared and protected from water degradation and maintenance costs may be pre-empted.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.